问题 选择题

从一位健康成年男性体内获得了一个精子和三种成熟的血细胞各一个,这四个细胞中含有的Y染色体总数最少可能是(   )

A.4条

B.2条

C.1条

D.0条

答案

答案:D

题目分析:男性体细胞中性染色体的组成是XY,从体细胞到生殖细胞精子染色体要两两分离,即性染色体就为X或Y,所以精子不一定含有Y染色体,血细胞包括红细胞、白细胞、血小板,红细胞和血小板中没有细胞核,所以不会有Y染色体,白细胞中含有细胞核,属于该男性的体细胞,一定有Y染色体,所以一个精子和三种成熟的血细胞含有的Y染色体数目最少可能是0条,而这四个细胞一共含有的Y染色体数目最多可能是1条。

点评:此题较新颖,有一定的难度,解答此题的关键是掌握三种血细胞的特点,只有白细胞有细胞核。

阅读理解

A blind schoolgirl has become the youngest interpreter (口译员) when she is only ten years

Alexia Sloane is from Cambridge. She was told by the doctor she had a brain tumour (脑癌) when she was on holiday "with her parents in France. After that the two-year-old girl became blind.

Though the little girl can't see anything, she has great talent for languages and at the age of 10 she is already fluent (流利的) in English, French, Spanish and Chinese-and is learning German.

Now her dream of working as an interpreter has come true. East of England MEP (欧盟议员) Robert Sturdy invited her to the European Parliament (议会). "Usually a person who enters the European Parliament should be 14 at least. So it was amazing for Alexia to work there at the age of 10. " said Alexia's mother Isabelle. Alexia can speak three languages since birth. As her mum is hah" French and half Spanish and her dad Richard is English. " She has always been very good at languages and shown an interest from a very young age. " added Isabelle, who also has a four-year-old daughter Melissa.

Alexia has dreamed of becoming an interpreter since she was six and chose to go to the European Parliament as her prize when she won the Young Achiever Community Award of the Year (年度青年成就奖). She asked if she could learn from the interpreters and HEP Robert Sturdy agreed to take her along as his guest. " It was fantastic and I decided to become an interpreter, "said Alexia. "Nothing can stop me. "

小题1:How old is the youngest interpreter according to the passage?

A.4.

B.6.

C.10.

D.14.小题2:When did Alexia Sloane become blind?

A.When she was born.

B.After she had a brain tumour.

C.After she became an interpreter.

D.When she was on holiday with her parents.小题3:Who offered Alexia the chance of working as an interpreter?

A.Richard.

B.Isabelle.

C.Melissa.

D.Robert Sturdy.小题4:What is right about Alexia Sloane?

A.She can speak five language fluently.

B.She is a talented language learner.

C.She is the only child in the family.

D. She went to France on holiday after she won the award.小题5:What do you think is the meaning of the sentence "Nothing can stop me. "?

A.Never give up.

B.Believe in yourself.

C.Nothing is impossible.

D.Failure is the mother of success.

单项选择题